Tip Sheets

Plants to beat the first summer heat

Media Contact

Lindsey Knewstub

The National Weather Service warns of above-normal temperatures for the northeastern region of the United States through Thursday. Cornell University experts comment on the year’s first summer heat and explain how it may affect plants.

Jessica Spaccio

Climatologist, Northeast Regional Climate Center

Jessica Spaccio is a climatologist with the Northeast Regional Climate Center at Cornell University and recently helped create a tool called the Water Deficit Calculator, giving farmers estimates of the soil water content accessible by crops.

Spaccio says:

“A heat wave in our area is defined as three consecutive days that reach 90 degrees Fahrenheit or hotter. Through Tuesday, forecasts show high temperatures near 90 degrees Fahrenheit, giving the possibility for a heat wave. An influx of moisture will also bring humid conditions, making it feel hotter.”

“Normally, high temperatures are in the mid-70s during this part of June.”

Donald Rakow

Associate Professor

With temperatures on the rise, Donald Rakow, associate professor in the School of Integrative Plant Science at Cornell University, explains some crops may fade quicker in the heat but most plants will recuperate as moderate temperatures set in later in the week.

Rakow says: 

“The current heat wave is a substantial departure from the cool, relatively wet weather we’ve experienced for much of this spring. Flowers of species that were in full bloom, such as iris and rhododendrons, will probably wilt and fade more quickly than they would have if the cooler temperatures had remained.

“If daytime highs in the 80s and 90s persist, cool season vegetables like spinach, lettuce, and kale may bolt (go to flower), thus limiting their palatability.

“Recent transplants need extra watering during the heat of the day, although a certain amount of midday wilting of the foliage is to be expected, due to excessive transpirational water loss.

“With temperatures expected to moderate later in the week, most plants are likely to bounce back from this early taste of summer.”

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